Abstract: The present invention relates to optical memories for storing data on the surface of an information-supporting medium including pre-formatted patterns. Such a memory may constitute a random access mass memory, and it may be read/write memory or it may be a write-once memory. The operations of writing to the memory and reading from the memory are based on the optical interaction which occurs at the point of impact of an incident optical beam which causes local changes in optical characteristics which are representative of the data when data is being written, and which produce optical modulation detectable by photoelectric means during data reading. The invention provides an optical memory in which the illumination mode common to reading data and to detecting pre-formatting patterns is modified in order to allow for operation in a standby mode or in order to delete areas reserved for storing data, for example.

Abstract: The optical head in the recording-reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

Abstract: An optical head is provided for an information carrier recording-reading device. Such an optical head comprises a pivoting mirror for reflecting the light towards the data carrier. According to the invention, this pivoting mirror is mounted on a pivoting seat having a sliding surface and resting on the sliding surface of the cradle shaped base. Said mirror is mounted on the seat so that the center of curvature of the sliding surfaces is in the reflecting plane of the mirror. Adjustment of the orientation of the mirror is thus made easy.

Abstract: The optical head in the recording - reading device of a data carrier comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source on to the data carrier via a reflecting or deviating mirror. According to the invention the rotation axis of this mirror is in the plane of the entrance pupil and of the focus of the focusing lens.

Abstract: A device makes it possible to eliminate the imbalance of a deviating mirror of an optical system which illuminates a data medium or support when that mirror is subject to rapid displacement. The imbalance is cancelled by the use of a photodetector device which receives the light reflected by a reflecting element positioned around the objective of the optical system which illuminates the medium. A control device then makes it possible to control the position of the mirror based upon the light given off by the reflecting element.

Abstract: The optical head in a data carrier recording-reading device comprises a semiconductor laser source. A lens makes it possible to focus the beam from this source. A polarization beam splitter makes it possible to deflect the beam reflected by this carrier towards a group of photodetectors. According to the invention the splitter is an isosceles prism, which serves as an anamorphotic-splitting means. A quarter-wave plate is bonded to one of the faces of the prism. A planoconvex lens can also be bonded to the other face of the prism upstream of the photodetector.

Abstract: An optical device for recording and reading on a data carrier is provided with first optical means forming a composite source of radiant energy comprising a first semiconductor-laser source for producing a polarized reading beam, a second semiconductor-laser source for producing a polarized recording beam, the two directions of polarization being at right angles to each other, and an optical element for combining the two beams followed by a polarizer. The device is also provided with second optical means comprising an optical separating element, a quarter-wave plate and an optical system for focusing the two reading and recording components after reflection from the tracks of the disk on two distinct zones of an optoelectronic detection device.

Abstract: Optical device for giving access to a track carried on a moving data carrier incorporating a moving element comprising a galvanometric mirror and a focusing objective movable relative to the data carrier and a fixed light energy source incorporating at least one laser emitter. Magnifying optical means of the afocal type are also inserted between the moving element and the light energy source. The magnification is sufficient to ensure that the beam emerging from the optical means completely covers the entrance pupil of the objective. As a result of this arrangement, the beam of light reaching the moving element remains a beam of parallel rays, no matter what the position of said element relative to the light energy source.

Abstract: An optical device for forming a stigmatic image of a laser source positioned at a predetermined point is intended to illuminate a reflecting surface while also providing a separation between the beam emerging from the source and the beam reflected from the surface. The device comprises a cube placed against a converging lens, the dimensions of the assembly thus formed being such that the cube face remote from the lens passes through a Weierstrass point of the spherical refracting surface formed by the lens. The laser source is positioned at the Weierstrass point. The cube is formed by two prisms cemented together, the interface being treated so as to have a polarization-separating effect.